src/third_party/mozjs/js/src/jit/x64/MacroAssembler-x64.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sts=4 et sw=4 tw=99:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "MacroAssembler-x64.h"
#include "jit/MoveEmitter.h"
#include "jit/IonFrames.h"

#include "jsscriptinlines.h"

using namespace js;
using namespace js::jit;

void
MacroAssemblerX64::setupABICall(uint32_t args)
{
    JS_ASSERT(!inCall_);
    inCall_ = true;

    args_ = args;
    passedIntArgs_ = 0; 
    passedFloatArgs_ = 0;
    stackForCall_ = ShadowStackSpace;
}

void
MacroAssemblerX64::setupAlignedABICall(uint32_t args)
{
    setupABICall(args);
    dynamicAlignment_ = false;
}

void
MacroAssemblerX64::setupUnalignedABICall(uint32_t args, const Register &scratch)
{
    setupABICall(args);
    dynamicAlignment_ = true;

    movq(rsp, scratch);
    andq(Imm32(~(StackAlignment - 1)), rsp);
    push(scratch);
}

void
MacroAssemblerX64::passABIArg(const MoveOperand &from)
{
    MoveOperand to;
    if (from.isDouble()) {
        FloatRegister dest;
        if (GetFloatArgReg(passedIntArgs_, passedFloatArgs_++, &dest)) {
            if (from.isFloatReg() && from.floatReg() == dest) {
                // Nothing to do; the value is in the right register already
                return;
            }
            to = MoveOperand(dest);
        } else {
            to = MoveOperand(StackPointer, stackForCall_);
            stackForCall_ += sizeof(double);
        }
        enoughMemory_ = moveResolver_.addMove(from, to, Move::DOUBLE);
    } else {
        Register dest;
        if (GetIntArgReg(passedIntArgs_++, passedFloatArgs_, &dest)) {
            if (from.isGeneralReg() && from.reg() == dest) {
                // Nothing to do; the value is in the right register already
                return;
            }
            to = MoveOperand(dest);
        } else {
            to = MoveOperand(StackPointer, stackForCall_);
            stackForCall_ += sizeof(int64_t);
        }
        enoughMemory_ = moveResolver_.addMove(from, to, Move::GENERAL);
    }
}

void
MacroAssemblerX64::passABIArg(const Register &reg)
{
    passABIArg(MoveOperand(reg));
}

void
MacroAssemblerX64::passABIArg(const FloatRegister &reg)
{
    passABIArg(MoveOperand(reg));
}

void
MacroAssemblerX64::callWithABIPre(uint32_t *stackAdjust)
{
    JS_ASSERT(inCall_);
    JS_ASSERT(args_ == passedIntArgs_ + passedFloatArgs_);

    if (dynamicAlignment_) {
        *stackAdjust = stackForCall_
                     + ComputeByteAlignment(stackForCall_ + STACK_SLOT_SIZE,
                                            StackAlignment);
    } else {
        *stackAdjust = stackForCall_
                     + ComputeByteAlignment(stackForCall_ + framePushed_,
                                            StackAlignment);
    }

    reserveStack(*stackAdjust);

    // Position all arguments.
    {
        enoughMemory_ &= moveResolver_.resolve();
        if (!enoughMemory_)
            return;

        MoveEmitter emitter(*this);
        emitter.emit(moveResolver_);
        emitter.finish();
    }

#ifdef DEBUG
    {
        Label good;
        testq(rsp, Imm32(StackAlignment - 1));
        j(Equal, &good);
        breakpoint();
        bind(&good);
    }
#endif
}

void
MacroAssemblerX64::callWithABIPost(uint32_t stackAdjust, Result result)
{
    freeStack(stackAdjust);
    if (dynamicAlignment_)
        pop(rsp);

    JS_ASSERT(inCall_);
    inCall_ = false;
}

void
MacroAssemblerX64::callWithABI(void *fun, Result result)
{
    uint32_t stackAdjust;
    callWithABIPre(&stackAdjust);
    call(ImmWord(fun));
    callWithABIPost(stackAdjust, result);
}

static bool
IsIntArgReg(Register reg)
{
    for (uint32_t i = 0; i < NumIntArgRegs; i++) {
        if (IntArgRegs[i] == reg)
            return true;
    }

    return false;
}

void
MacroAssemblerX64::callWithABI(Address fun, Result result)
{
    if (IsIntArgReg(fun.base)) {
        // Callee register may be clobbered for an argument. Move the callee to
        // r10, a volatile, non-argument register.
        moveResolver_.addMove(MoveOperand(fun.base), MoveOperand(r10), Move::GENERAL);
        fun.base = r10;
    }

    JS_ASSERT(!IsIntArgReg(fun.base));

    uint32_t stackAdjust;
    callWithABIPre(&stackAdjust);
    call(Operand(fun));
    callWithABIPost(stackAdjust, result);
}

void
MacroAssemblerX64::handleFailureWithHandler(void *handler)
{
    // Reserve space for exception information.
    subq(Imm32(sizeof(ResumeFromException)), rsp);
    movq(rsp, rax);

    // Ask for an exception handler.
    setupUnalignedABICall(1, rcx);
    passABIArg(rax);
    callWithABI(handler);

    Label entryFrame;
    Label catch_;
    Label finally;
    Label return_;

    loadPtr(Address(rsp, offsetof(ResumeFromException, kind)), rax);
    branch32(Assembler::Equal, rax, Imm32(ResumeFromException::RESUME_ENTRY_FRAME), &entryFrame);
    branch32(Assembler::Equal, rax, Imm32(ResumeFromException::RESUME_CATCH), &catch_);
    branch32(Assembler::Equal, rax, Imm32(ResumeFromException::RESUME_FINALLY), &finally);
    branch32(Assembler::Equal, rax, Imm32(ResumeFromException::RESUME_FORCED_RETURN), &return_);

    breakpoint(); // Invalid kind.

    // No exception handler. Load the error value, load the new stack pointer
    // and return from the entry frame.
    bind(&entryFrame);
    moveValue(MagicValue(JS_ION_ERROR), JSReturnOperand);
    movq(Operand(rsp, offsetof(ResumeFromException, stackPointer)), rsp);
    ret();

    // If we found a catch handler, this must be a baseline frame. Restore state
    // and jump to the catch block.
    bind(&catch_);
    movq(Operand(rsp, offsetof(ResumeFromException, target)), rax);
    movq(Operand(rsp, offsetof(ResumeFromException, framePointer)), rbp);
    movq(Operand(rsp, offsetof(ResumeFromException, stackPointer)), rsp);
    jmp(Operand(rax));

    // If we found a finally block, this must be a baseline frame. Push
    // two values expected by JSOP_RETSUB: BooleanValue(true) and the
    // exception.
    bind(&finally);
    ValueOperand exception = ValueOperand(rcx);
    loadValue(Operand(esp, offsetof(ResumeFromException, exception)), exception);

    movq(Operand(rsp, offsetof(ResumeFromException, target)), rax);
    movq(Operand(rsp, offsetof(ResumeFromException, framePointer)), rbp);
    movq(Operand(rsp, offsetof(ResumeFromException, stackPointer)), rsp);

    pushValue(BooleanValue(true));
    pushValue(exception);
    jmp(Operand(rax));

    // Only used in debug mode. Return BaselineFrame->returnValue() to the caller.
    bind(&return_);
    movq(Operand(rsp, offsetof(ResumeFromException, framePointer)), rbp);
    movq(Operand(rsp, offsetof(ResumeFromException, stackPointer)), rsp);
    loadValue(Address(rbp, BaselineFrame::reverseOffsetOfReturnValue()), JSReturnOperand);
    movq(rbp, rsp);
    pop(rbp);
    ret();
}

Assembler::Condition
MacroAssemblerX64::testNegativeZero(const FloatRegister &reg, const Register &scratch)
{
    movqsd(reg, scratch);
    subq(Imm32(1), scratch);
    return Overflow;
}